This invention relates to a method and apparatus for folding diapers and, more particularly, to the structure and operation of a crank actuated tucker blade for transversely folding diapers being advanced in a series.
Disposable diapers are currently made at high speed--from about 300 to about 400 units per minute on machines that bring together a moisture impervious web such as polyethylene, a fluff core and a web of nonwoven material providing the diaper surface next to the infant's body. A typical machine can be seen in U.S. Pat. No. 4,081,301. After the diapers have been formed and are being advanced in a continuous series or stream, there is a problem of maintaining the line at operating speed yet being able to sort out or cull imperfectly made diapers just ahead of the final folding operation before stacking and insertion into packages for retail sale.
According to the instant invention, this problem has been resolved through the use of a novel crank-actuated tucker blade which operates reliably at the speeds above 500 units/min.--and also provides the important facility of being able to "cull". Even in the best operated machines, there appears, from time-to-time, a defective diaper, which has to be excluded from the packaging operation. It is impossible to do this manually at the speeds indicated--and current folding devices do not provide for deactivation for culling and re-engagement for folding without great complexity and cost, or speed limitations or both. Through the practice of the invention, the acceptable diapers are transversely folded from a position of advance in a horizontal path for delivery into a vertical path for packaging. The defective diapers are culled by displacing the folding mechanism so that the impaired diapers proceed along the original path and thereby do not get to the packaging station--now at speeds beyond 500 units/min. without interruption of the continuous orbiting motion of the folding device thus providing higher speed culling, a lower cost device not requiring disengaging of the drive means and higher reliability.
The novel folding mechanism makes use of an orbiting blade which passes through the horizontal path of advancement of the stream of diapers. Although orbiting mechanisms per se are not novel--see, for example, co-owned U.S. Pat. No. 3,256,012--orbiting mechanisms have not been used for the purposes of this invention nor have they provided the advantages attendant to the instant invention. One significant advantage of the instant invention is the ability to cull defective diapers at high speed by displacing the orbiting tucker blade to a position of non-engagement with the stream of diapers. Displacement mechanisms also are not novel but again lack the structure and operation of the instant invention, compare, for example, co-owned U.S. Pat. No. 3,740,049.
Other advantages and objects of the invention may be seen in the details of the ensuing specification.